Liberals do this kind of thing regularly. The most extreme exaggeration possible will always be used. Here we have rape, but they also like things like Nazi, Hitler, lynching, KKK, White Supremacist, and on like that.
They use these terms because they know that the more extreme the hyperbole, the more likely it is that it will be reported. And it works. If they did not use extreme hyperbole, they would be ignored, and they know this.
Therefore, they wind up competing with each other to see who can come up with the most vile and outrageous statements. And that is why we now read that Trump is worse than rape. It is just another step in the never-ending competition for publicity.